TW201409087A - Optical element and concentrated photovoltaic device - Google Patents

Abstract

Provided are an optical element and a concentrated photovoltaic device that are able, even in environments in which there are large variations in temperature, to prevent warpage, and stress deformation in the optically functional pattern formed on the element surface. The optical element (4) of the concentrating solar power device (1) is for concentrating solar light, and includes: a glass substrate (5); and a sheet-like molded body (6) that comprises an organic resin, has one surface that has a Fresnel lens pattern (6a), and another surface that is bonded to the glass substrate (5). The sheet-like formed body (6) has: a tensile elastic modulus of 1500MPa or less; a linear expansion coefficient of 7.0x10<SP>-5</SP>/ DEG C or below; an average transmittance of 85% or more, in a wavelength band of 350-1850nm at a thickness of 400μm; and a haze value of 1.0% or less.

Description

Optical component and concentrating solar power generation device

The present invention relates to an optical element in which an optical function pattern is formed on a surface, and a concentrating solar power generation device.

In recent years, the use of natural energy has attracted attention, and one of them is solar power generation that converts solar energy into electricity by solar cells. Conventionally, such solar power generation obtains large electric power in order to improve power generation efficiency (photoelectric conversion efficiency), and is arranged on the front side of a plurality of solar cell elements disposed on the same plane, and is configured to collect sunlight for collecting solar cells. A concentrating solar power generation device including a lens (optical element) (see, for example, Patent Document 1).

In the concentrating solar power generation device, since the sunlight is collected by the collecting lens and the light is received by the solar cell element, the size of the solar cell element of a high price can be reduced. Therefore, it is possible to reduce the cost of the entire power generating device. Therefore, the concentrating solar power generation device tends to be widely used as a power supply application because of the long sunshine hours and the wide area in which the concentrating surface can be increased.

Advanced technical literature Patent literature

Patent Document 1 JP-A-2006-343435

In the concentrating solar power generation device of the above-mentioned Patent Document 1, a transparent glass substrate is attached to the surface of the solar light incident surface of the sheet-shaped concentrating lens made of PMMA resin based on environmental resistance and the like.

It is suitable for the area where power is generated by the concentrating solar power generation unit (a wide area that can be set up with long sunshine hours and even a large area of the concentrating surface), such as the southwestern part of the United States (Nevada, etc.), the Mediterranean coast of Europe, the Middle East, etc. However, the temperature difference between day and night in these areas and the temperature difference between summer and winter are very large.

Therefore, when the PMMA resin is used as the resin material for forming the collecting lens of the concentrating solar power generation device, the temperature difference (the temperature difference) is large, and the temperature difference causes the thermal expansion and contraction of the collecting lens. For example, in an environment with a temperature difference of about 40 degrees, a collecting lens composed of a PMMA resin having a size of 1 m ² generates thermal expansion and contraction of about several mm. When the collecting lens generates thermal expansion and contraction of about several mm, the rigidity of the glass substrate causes bending of the edge portion side of the collecting lens, so that a part of the collected light is deviated from the light receiving region of the solar cell element, resulting in a decrease in power generation efficiency. .

Further, a concentrating lens of the concentrating solar power generation device is formed of an fluorenone resin, and in the configuration of the concentrating lens and the glass substrate, the linear expansion coefficient is in the glass (0.09 × 10 ^-5 / ° C) and the fluorenone resin ( There is a great difference between 25 and 30 × 10 ^-5 / ° C). In addition, the hardness of the fluorenone resin is low.

Therefore, when an fluorenone resin is used as the resin material for forming the collecting lens of the concentrating solar power generation device, since the linear expansion coefficient of the glass to be entangled resin is greatly different, and the hardness of the fluorenone resin is low, the temperature difference is In a region where the temperature difference is large, there is a fear that the stress is applied to the Fresnel lens portion of the fine concavo-convex shape of the collecting lens made of the fluorenone resin to cause deformation. Thus, when the Fresnel lens pattern portion of the collecting lens is deformed, part of the collected light may deviate from the light receiving region of the solar cell element, resulting in a decrease in power generation efficiency.

Here, an object of the present invention is to provide an optical element and a concentrating solar power generation device capable of preventing an optical function pattern (Fresnel lens, etc.) formed by bending or stress due to stress even in an environment with a large temperature difference. Deformation.

In order to achieve the above object, the invention of claim 1 is an optical element comprising: a light-transmitting substrate; and a sheet-like molded body made of an organic resin, having an optical function pattern on one surface and the light-transmitting surface on the other surface The sheet-like formed body has a tensile modulus of 1500 MPa or less, a linear expansion coefficient of 7.0×10 ⁻⁵ /° C. or less, and a thickness of at least 400 μm. The average transmittance is 85% or more, and the haze value is 1.0% or less. When a light having ultraviolet rays is irradiated for 600 hours at an illuminance of 1 kW/m ² using a metal halide lamp, at least 350 nm to 600 nm. The average transmittance of the wavelength bandwidth is reduced by less than 2%. Further, in the present invention, the linear expansion coefficient is a value measured at 30 ° C according to JIS K7197, and the tensile elastic modulus is a value measured in accordance with JIS K7127.

The invention of claim 2 is characterized in that the light-transmitting substrate is made of a glass substrate.

The invention of claim 3 is characterized in that the sheet-like forming system is formed using a thermoplastic polymer composition containing an acrylic block copolymer (A) and an acrylic resin (B); and the above-mentioned thermoplastic polymer composition, the above acrylic acid The block-like copolymer (A) is an acrylic block copolymer having at least one of the following structures: a methyl group bonded to each other at both ends of the polymer block (a1) mainly composed of an acrylate unit The acrylate unit is a structure of the main polymer block (a2); and the weight average molecular weight is 10,000-100,000; The acrylic block copolymer (A) contains an acrylic block copolymer (A1) having a polymer block (a2) content of 40% by mass or more and 80% by mass or less; and a polymer block (a2) The acrylic block copolymer (A2) having a content of 10% by mass or more and less than 40% by mass; the acrylic resin (B) is mainly composed of a methacrylate unit; the acrylic block copolymer (A) and an acrylic resin ( The mass ratio of B) [(A)/(B)] is 97/3 to 10/90.

The invention of claim 4 is characterized in that the sheet-like formed body contains an ultraviolet absorber.

The invention of claim 5 is characterized in that the light-transmitting substrate contains an ultraviolet absorber.

The invention of claim 6 is characterized in that an ultraviolet absorbing layer is formed on a surface of the light-transmitting substrate opposite to the surface on which the sheet-shaped formed body is attached.

The invention of claim 7 is characterized in that the surface of the light-transmitting substrate opposite to the surface of the sheet-shaped formed body is subjected to an antifouling treatment.

The invention of claim 8 is characterized in that the surface of the light-transmitting substrate opposite to the surface of the sheet-shaped formed body is subjected to an anti-reflection treatment.

The invention of claim 9 is characterized in that the peeling strength of the sheet-like formed body following the light-transmitting substrate is 25 N/25 mm or more. Further, the peeling strength of the present invention is a value measured by a method of measuring 180-degree peeling strength in accordance with JIS K685-2.

The invention of claim 10 is characterized in that after the sheet-like molded body is subjected to one of plasma treatment, excimer treatment, and corona treatment on the adhesion surface of the light-transmissive substrate, the permeation is performed. The optical substrate is followed by the bonding surface.

The invention of claim 11 is characterized in that the optical function pattern formed on the sheet-like formed body is a Fresnel lens pattern.

The concentrating solar power generation device according to the invention of claim 12, comprising: an optical element that collects sunlight; and a solar cell element that receives sunlight collected by the optical element and performs photoelectric conversion; and the optical element The optical component of claim 11.

The invention of claim 13 is characterized in that the optical element of claim 3 is characterized in that at least one of the sheet-shaped molded body and the light-transmitting substrate contains an ultraviolet absorber.

The invention of claim 14 is the optical element of claim 13, wherein the optical function pattern formed on the sheet-like formed body is a Fresnel lens pattern.

The concentrating solar power generation device according to the invention of claim 15 further comprising: an optical element that collects sunlight; and a solar cell element that receives the sunlight collected by the optical element and performs photoelectric conversion; and the optical element The optical component of claim 14.

The invention of claim 3 is characterized in that the optical element of claim 3 is characterized in that an ultraviolet absorbing layer is formed on a surface of the light-transmitting substrate opposite to the surface on which the sheet-shaped formed body is attached.

The invention of claim 17 is the optical element of claim 16, wherein the optical function pattern formed on the sheet-like formed body is a Fresnel lens pattern.

The concentrating solar power generation device according to the invention of claim 18, comprising: an optical element that collects sunlight; and a solar cell element that receives sunlight collected by the optical element and performs photoelectric conversion; and the optical element The optical component of claim 17.

According to the optical element of the present invention, the sheet-like molded body comprising the organic resin of the light-transmitting substrate has a tensile modulus of 1500 MPa or less, a linear expansion coefficient of 7.0 × 10 ^-5 /° C. or less, and a thickness of 400 μm. The average transmittance at least in the visible light wavelength band is 85% or more, and the haze value is 1.0% or less.

Therefore, the sheet-like formed body has a good light transmittance, and the tensile elastic modulus is a small value of 1500 MPa or less, so that the amount of bending is small even in an environment where the temperature changes greatly, and the linear expansion coefficient is 7.0 × Since 10 ^-5 / ° C or less is smaller than the fluorenone resin, the deformation of the optical function pattern formed on the surface can be suppressed to be small even in an environment where the temperature changes greatly.

Further, in the optical element according to the present invention, the thickness of the area of the light-transmitting substrate is 5 mm or less at an area of 1 m ² , and the thickness of the sheet-shaped molded body is 1/15 or more of the thickness of the light-transmitting substrate. It is preferably formed by using the SUV-W151E unit manufactured by Iwasaki Electric Co., Ltd., using a water-cooled metal halide lamp (M04-L21WBX/SUV) with a rated power of 4 kW, and a UV of 1 kW/m ² in the wavelength range of 290 to 450 nm. When the ultraviolet ray-containing light is irradiated for 600 hours under illuminance conditions, the average light transmittance at least in the wavelength band of 350 to 600 nm is reduced by 2% or less.

Therefore, the sheet-like formed body can maintain good light transmittance for a long period of time.

Further, according to the concentrating solar power generation device of the present invention, since the optical element of the present invention is disposed as a collecting lens, it is possible to condense sunlight on the solar cell element for a long period of time even in an environment with a large temperature change. The area can maintain high power generation efficiency.

1‧‧‧Light collecting solar power generation unit

2‧‧‧Solar battery components

4‧‧‧Optical components

5‧‧‧Glass substrate (transparent substrate)

6‧‧‧Sheet shaped body

6a‧‧ Fresnel lens pattern (optical function pattern)

Fig. 1 is a cross-sectional view showing a schematic configuration of a concentrating solar power generation apparatus including an optical element according to an embodiment of the present invention.

Fig. 2 is a plan view showing the outline of the concentrating solar power generation device according to the embodiment of the present invention as seen from the sunlight incident side.

3A is a cross-sectional view showing a schematic configuration of a concentrating solar power generation device in which an ultraviolet absorbing layer is provided on the surface of an optical element.

3B is a cross-sectional view showing a schematic configuration of a concentrating solar power generation device in which an antifouling coating layer is provided on the surface of an optical element.

3C is a cross-sectional view showing a schematic configuration of a concentrating solar power generation device in which an antireflection coating layer is provided on the surface of an optical element.

Fig. 4A shows the measurement results of the light transmittance in the optical element of Example 1.

4B shows the measurement results of the light transmittance in the optical element of Comparative Example 1.

Hereinafter, the present invention will be described based on the embodiments shown in the drawings. 1 is a schematic cross-sectional view showing a schematic configuration of a concentrating solar power generation device including an optical element according to an embodiment of the present invention.

[Entire structure of concentrating solar power generation device]

As shown in Fig. 1, the concentrating solar power generation device 1 of the present embodiment includes the following main components: a solar battery element (solar battery unit) 2 that photoelectrically converts collected sunlight; and the solar battery element is mounted. The solar cell substrate 3 of 2; and the optical element 4 for collecting sunlight are disposed on the front side (sunlight incident side) facing the solar cell element 2. Further, in Fig. 1, L1 indicates sunlight incident on the optical element 4, and L2 indicates sunlight collected by the optical element 4.

The optical element 4 is configured by a light-transmitting substrate provided on the sunlight incident side, in particular, a glass substrate 5, and a sheet-shaped molded body 6 made of an organic resin, which is attached to the glass substrate 5 The surface of the side (the side facing the solar cell element) is translucent (the details of the sheet-like formed body 6 of the present invention will be described later). A Fresnel lens pattern 6a is formed concentrically on the surface of the sheet-like formed body 6 opposite to the glass substrate 5 (the side facing the solar cell element 2) for concentrating the incident sunlight. The light receiving area of the solar cell element 2. As described above, the sheet-like formed body 6 in which the Fresnel lens pattern 6a is formed functions as a collecting lens.

As shown in FIG. 2, in the concentrating solar power generation device 1, a plurality of solar cell elements 2 are mounted on a solar cell substrate at regular intervals, and a plurality of optical elements 4 face the respective solar cell elements 2 for receiving light. Areas are integrated on the same plane.

The glass substrate 5 and the sheet-like formed body can be subsequently joined by a conventional method such as thermocompression bonding or an adhesive, but it is preferably thermocompression bonded from the viewpoint of thickness accuracy and the like. In the embodiment, the glass substrate 5 and the sheet-like formed body 6 are thermocompression bonded and both are followed.

Moreover, it is more preferable that the peeling strength of the sheet-like molded body 6 following the glass substrate 5 is 25 N/25 mm or more, and it is more preferable to set it as 50 N/25 mm or more. When the peeling strength is 25 N/25 mm or more, the sheet-like formed body 6 can be surely prevented from being peeled off from the glass substrate 5 for a long period of time.

Further, before the glass substrate 5 and the sheet-like formed body 6, the electrode surface of the sheet-like molded body 6 and the glass substrate 5 is preferably subjected to a plasma treatment, and then attached to the glass substrate 5. When the surface of the sheet-like molded body 6 and the glass substrate 5 are subjected to a plasma treatment to perform surface modification, the adhesion to the glass substrate 5 can be further improved. Sex. Further, in addition to the plasma treatment, excimer treatment or corona treatment may be performed to perform surface modification.

Moreover, as a method of producing the optical element 4 in which the sheet-like molded body 6 is formed on the glass substrate 5, for example, a conventional hot press forming method or a vacuum build-up forming method can be used.

In the vacuum lamination method according to the embodiment of the present invention, the formed sheet and the mold are placed at a temperature close to room temperature to lower the pressure, and the bubbles between the sheet and the mold are removed, and then the upper and lower sides are uniformly heated while being heated. A method of producing a molded body by supplying pressure to transfer the shape of the mold to a sheet.

In any one of the hot press forming method and the vacuum lamination molding method, for example, a sheet-shaped film before molding may be thermocompression bonded to the glass, and a shaping die such as a nickel stamp may be placed on the film. A method of forming the sheet-like formed body 6 while applying pressure to the sheet-like molded body 6 while applying pressure to the glass/film/imprint while applying pressure.

Further, in addition to the above-described thermocompression bonding, the glass substrate 5 and the sheet-like molded body 6 may be an adhesive. The adhesive is preferably an acrylic resin-based adhesive or an oxime resin adhesive containing methyl methacrylate, an acrylic monomer or the like which has good light transmittance or weather resistance. In particular, it is preferred to use an adhesive composed of a resin of the same kind as the sheet-like formed body 6. Further, the coating thickness is preferably as thin as possible.

Each of the solar cell elements 2 and each of the optical elements 4 is positioned with good precision, and is sealed around the side surface between the solar cell substrate 3 and the optical element 4 to make moisture (moisture) or dust. The inside does not intrude into the space between the solar cell substrate 3 and the optical element 4. Further, the number or size of the solar cell elements 2 and the optical elements 4 arranged in the opposite direction can be arbitrarily set depending on the size or installation place of the concentrating solar power generation device 1.

[Details of Sheet Shaped Body 6]

The sheet-like formed body 6 of the present invention can form a thermoplastic polymer composition of the following acrylic block copolymer (A) and acrylic resin (B), which has advantages such as good transparency, weather resistance, and flexibility. .

In the above thermoplastic polymer composition, the acrylic block copolymer (A) is an acrylic block copolymer having at least one structure in a molecule: a polymer block mainly composed of an acrylate unit (a1) The two ends are respectively bonded to a polymer block (a2) mainly composed of a methacrylate unit; and the weight average molecular weight is 10,000 to 100,000; the above acrylic block copolymer (A) comprises: polymerization The acrylic block copolymer (A1) having a content of the block (a2) of 40% by mass or more and 80% by mass or less; and the acrylic block having a content of the polymer block (a2) of 10% by mass or more and less than 40% by mass Block copolymer (A2); the above acrylic resin (B) is mainly composed of methacrylate units; mass ratio of acrylic block copolymer (A) to acrylic resin (B) [(A)/(B) 〕 is 97/3~10/90.

Further, the acrylic block copolymer (A) is an acrylic block copolymer having at least one structure in the molecule: in the case of C The enoate unit is a structure in which both ends of the main polymer block (a1) are bonded to a polymer block (a2) mainly composed of a methacrylate unit, that is, (a2)-(a1) - (a2) structure ("-" in this structure means chemical bonding).

Further, the acrylic resin (B) is an acrylic resin mainly composed of a methacrylate unit. In view of the improvement in transparency, moldability, and the like of the sheet-like formed body composed of the thermoplastic polymer composition, a monomer of methacrylate or a copolymer mainly composed of a methacrylate unit is preferred.

The details of the above-described thermoplastic polymer composition in the present embodiment are described in International Publication WO2010/055798. The sheet-like formed body composed of the thermoplastic polymer composition (the formed body before the Fresnel lens pattern is formed on the surface) can be, for example, a conventional T-die method or a blow molding method. Manufacturing.

Further, a method of forming the Fresnel lens pattern 6a on the surface of the sheet-like formed body 6 composed of the thermoplastic polymer composition is, for example, a conventional die forming method, an injection molding method, and 2P (Photo Polymerization) using an ultraviolet curable resin. ) molding method, etc.

The physical properties of the sheet-like formed body 6 formed of the above thermoplastic polymer composition are as follows.

That is, the sheet-like molded body 6 has a tensile elastic modulus of 1,500 MPa or less, a linear expansion coefficient of 7.0 × 10 ^-5 /° C. or less, and an average transmittance of 85% or more with respect to a wavelength band of 350 to 1850 nm at a thickness of 400 μm. The degree is below 1.0%. In addition, the thickness of the glass substrate 5 is 5 mm or less when the area is 1 m ² , and the sheet-like formed body 6 is formed to have a thickness of 1/15 or more of the thickness of the glass substrate 5. Further, when a light having an ultraviolet wavelength band was irradiated with an illuminance of 1 kW/m ² for 600 hours using a metal halide lamp, the average light transmittance at a wavelength band of 350 to 600 nm was reduced by 2% or less.

The sheet-like formed body 6 of the present embodiment is formed using a thermoplastic polymer composition containing the above acrylic block copolymer (A) and an acrylic resin (B), and therefore, the tensile elastic modulus is lower than that of the PMMA resin, and linear. The coefficient of expansion is smaller than that of the ketone resin.

Therefore, the optical element 4 of the sheet-like formed body 6 is adhered to the glass substrate 5, and the amount of bending of the sheet-like formed body 6 is small even in a large temperature difference environment, and the Fresnel lens pattern 6a of the sheet-like formed body 6 is also obtained. The amount of deformation is also small. In this way, even in a large temperature difference environment, the light collected by the optical element 4 can be well received by the light receiving region of the solar cell element, and the decrease in light transmittance can be suppressed, and stable and good power generation efficiency can be maintained for a long period of time. .

Further, the sheet-like molded body 6 or/and the glass substrate 5 may be composed of an ultraviolet absorber. Further, as shown in FIG. 3A, an ultraviolet absorbing agent 7 can be formed by applying an ultraviolet absorber to the surface of the glass substrate 5 on the sunlight incident side. By constituting the ultraviolet rays that can absorb the sunlight incident on the optical element 4, it is possible to suppress the change in color or physical properties of the sheet-like molded body 6 by the ultraviolet rays, and it is possible to maintain good power generation efficiency for a long period of time.

Moreover, as shown in FIG. 3B, an antifouling coating agent 8 can be formed by applying an antifouling coating agent to the surface of the glass substrate 5 on the sunlight incident side. By performing the antifouling treatment, it is possible to suppress adhesion of sand, dust, etc. to the glass base. Since the sunlight of the plate 5 is incident on the surface of the side, the decrease in the light transmittance can be suppressed, whereby the good power generation efficiency can be maintained for a long period of time.

Further, as shown in FIG. 3C, an antireflection coating agent 9 may be formed by coating an antireflection coating agent on the surface of the glass substrate 5 on the sunlight incident side. By implementing the anti-reflection treatment, the transmittance of sunlight can be further increased, and the power generation efficiency can be further improved.

[Examples]

In the following, in order to evaluate the effects produced by the optical element 4 of the present invention described above, each of the optical elements having the configurations of the first to fourth embodiments of the present invention and the comparative examples 1 to 4 for comparison was evaluated.

[Example 1]

Produced in Example 1: for a linear expansion coefficient of 6.6 × 10 ^-5 / ° C, a tensile elastic modulus in the MD direction (longitudinal direction) of 300 MPa, and a tensile elastic modulus in the TD direction (width direction) of 200 MPa, methyl methacrylate (MMA) and butyl acrylate (BA), and mixtures of block copolymers of methyl acrylic resin (corresponding to the thermoplastic polymer composition) composed of a resin sheet having a thickness of 400μm (corresponds to the formation The sheet-shaped formed body before the Fresnel lens pattern) is subjected to the following plasma treatment for improving the adhesion, and then bonded to a transparent glass substrate having a thickness of 2 mm at a temperature of 175 ° C. .

The above block copolymer uses B-1 of MMA/BA = 50/50 and B-2 of MMA/BA = 30/70. As the methacrylic resin, PARAPET H1000B (manufactured by Kuraray Co., Ltd.) was used. B-1 is set to 50 mass%, B-2 is 20% by mass, methacrylic resin is a mixture of 30% by mass of the obtained thermoplastic resin composition.

The plasma treatment was carried out as follows. The atmospheric pressure plasma device APG-500 manufactured by Kasuga Electric Co., Ltd. was used, and the irradiation was performed under the conditions of a supply air flow rate of 190 NL/min, a rated output power of 450 to 500 W, and an irradiation distance of 10 mm. The area of the atmospheric plasma irradiation was about 3 cm ² , and the entire head of the resin sheet was subjected to plasma irradiation by moving the head under the condition that the plasma was irradiated for about 1 second in the same place.

Then, the change in transmittance of light before and after irradiation for 600 hours with a metal halide lamp (illuminance of 1 kW/mm ² in a wavelength band of 290 to 450 nm (ultraviolet wavelength band)) was measured on the glass substrate side of the optical element. 4A shows the measurement results of the light transmittance of Example 1. A is a transmittance characteristic after irradiation for 600 hours, and b is a transmittance characteristic before irradiation (0 time of irradiation).

As is apparent from the measurement results of Fig. 4A, the optical element of the above-described first embodiment had a good transmittance even if it was substantially unchanged after being irradiated for 600 hours with a metal halide lamp. Further, the optical element irradiated for 600 hours has a slightly improved transmittance in the wavelength band of 350 to 400 nm.

[Embodiment 2]

In the second embodiment, the optical element produced under the same conditions as in the first embodiment was cut into a size of 50 cm square, and the optical element was placed on a flat test stand to measure the temperature change (the above-mentioned Fresnel lens pattern). The amount of bending of the sheet-like formed body in the previous stage to be formed.

In the measurement of the amount of bending, the amount of bending of the peripheral portion and the central portion of the resin sheet at room temperature was 0 mm. Thereafter, when the temperature was raised from room temperature by 65 ° C for a predetermined period of time, the amount of bending of the peripheral portion of the resin sheet was smaller than 0.5 mm. Further, the amount of bending of the central portion is approximately 0 mm.

[Example 3]

In the third embodiment, a resin sheet similar to that of the first embodiment was produced by a conventional vacuum lamination molding method in which a collecting lens having a Fresnel lens pattern having a square size of 20 cm was bonded to a transparent glass substrate. element.

Thereafter, a 10 mm square light-receiving sensor is placed at a focus position of the Fresnel lens pattern for the fixed optical element, and laser light is incident from the glass substrate side (wavelength 532 nm, spot diameter 5 mm) To scan the entire surface of the Fresnel lens pattern, and measure the amount of light received by the light sensor. Laser light is incident in the same state in which the optical element is removed (wavelength 532 nm, spot diameter 5 mm) The amount of light received by the light receiving sensor when the Fresnel lens pattern is absent is measured.

The amount of light received by the light receiving sensor by the Fresnel lens pattern surface of the optical element, and the amount of light received by the light receiving sensor by the Fresnel lens pattern of the optical element relative to the Fresnel-free lens pattern The ratio of the amount of light received by the light sensor (light collecting efficiency) was evaluated. The results show that the lens collection efficiency of the Fresnel lens pattern of the optical element in this embodiment is 90.07%.

[Example 4]

In the fourth embodiment, the optical element having the same configuration as that of the third embodiment was evaluated for the same light collection efficiency as that of the third embodiment under the condition that the temperature was raised from room temperature to 50 ° C for a specific period of time. The results show that the lens collection efficiency of the Fresnel lens pattern of the optical element in this embodiment is 89.96%. From the results, it was found that there was no change in the light collection efficiency of the lens at 25 ° C and 50 ° C at room temperature.

Further, with respect to the glass substrate side of the optical element of the present embodiment, when the laser light is incident on a position 75 mm away from the center of the Fresnel lens pattern surface, the spot shape is diffused in the focal position, at temperatures of 15 ° C and 50 ° C. Observe. The results show that the spread of the spot shape of the laser light at a temperature of 15 ° C or 50 ° C is small.

[Comparative Example 1]

In Comparative Example 1, a commercially available 3:10-thick acrylic resin sheet (manufactured by KURARAY Co., Ltd.: trade name [PARAPET GH-SN]) was used instead of the optical element of Example 1, and a metal halide lamp (in wavelength) was used in the same manner as in Example 1. The bandwidth of 290 to 450 nm (ultraviolet wavelength band width) was measured by a change in light transmittance before and after irradiation for 600 hours at an illumination of 1 kW/mm ² . 4B shows the measurement results of the light transmittance in Comparative Example 1, where a is the transmittance characteristic after irradiation for 600 hours, and b is the transmittance characteristic before the start of irradiation (irradiation time 0).

As is apparent from the measurement results of FIG. 4B, the acrylic resin sheet having a thickness of 3 mm was greatly reduced in light transmittance at a wavelength band of 350 to 600 nm after being irradiated with a metal halide lamp for 600 hours. In particular, the decrease on the side of the short wavelength region is more remarkable. That is, the single molded body of the acrylic resin sheet is inferior in light resistance.

[Comparative Example 2]

In Comparative Example 2, an optical element was produced in the same manner as in Example 1 except that a resin sheet used in place of the optical element of Example 1 was used instead of the PMMA sheet having a tensile modulus of 3300 MPa and a thickness of 400 μm. The amount of bending of the optical element at the time of temperature change was measured under the conditions.

The amount of bending of the peripheral portion and the central portion of the optical element at room temperature during the measurement of the amount of bending was 0.0 mm. The amount of warpage of the peripheral portion of the optical element was 2.1 mm when the temperature was raised from room temperature to 65 ° C over a certain period of time. As a result, it was revealed that the amount of warpage was larger as compared with Example 2.

[Comparative Example 3]

In the comparative example 3, the resin sheet used in the first embodiment was replaced with the fluorene ketone resin sheet, and an optical element formed by laminating a collecting lens on a transparent glass substrate was prepared by a conventional vacuum lamination molding method in the same manner as in the third embodiment. The collector lens is formed with a Fresnel lens pattern having a size of 20 cm square.

Then, in the same manner as in the third embodiment, a 10 mm square light-receiving sensor was placed at the focus position of the Fresnel lens pattern for the fixed optical element, and laser light was incident from the glass substrate side (wavelength 532 nm, spot diameter 5 mm). ) scanning the entire surface of the Fresnel lens pattern surface, measuring the amount of light received by the light sensor, and injecting laser light in the same state in which the optical element is removed (wavelength 532 nm, spot diameter 5 mm) The amount of light received by the light receiving sensor when the Fresnel lens pattern is absent is measured.

The amount of light received by the photoreceptor through the Fresnel lens pattern surface of the optical element, and the Fresnel through the optical element The lens pattern surface was evaluated by the ratio of the amount of light received by the light receiving sensor to the amount of light received by the light sensor (the light collecting efficiency of the lens). As a result, it was revealed that the lens collection efficiency of the Fresnel lens pattern surface of the optical element in Comparative Example 3 was 87.9%, which was lower than that of Example 3.

[Comparative Example 4]

Comparative Example 4 is an optical element (an optical element formed by laminating an fluorene ketone resin sheet having a Fresnel lens pattern formed on a glass substrate) in the same manner as in Comparative Example 3, and the temperature is raised from room temperature to a predetermined time. The lens collection efficiency was evaluated in the same manner as in Example 3 (Comparative Example 3) at 50 °C. As a result, it was revealed that the lens collection efficiency of the Fresnel lens pattern surface of the optical element in Comparative Example 4 was 80.8%. It is lower than that in the case of the fourth embodiment. In addition, the light collection efficiency was significantly lowered as compared with Comparative Example 3 and when heat was not supplied.

Further, with respect to the glass substrate side of the optical element of Comparative Example 4, the diffusion state of the spot shape in the focus position when the laser light was incident at a position 75 mm away from the center of the Fresnel lens pattern surface was at a temperature of 15 ° C and Observation was carried out at 50 °C. The results show that the diffusion of the spot shape of the laser light is small at a temperature of 15 ° C, but the diffusion of the spot shape of the laser light at 50 ° C becomes large.

[Reciprocal reference to related applications]

The present application claims priority on Japanese Patent Application No. 2012-153534, filed on Jan.

1‧‧‧Light collecting solar power generation unit

2‧‧‧Solar battery components

3‧‧‧Solar battery substrate

4‧‧‧Optical components

5‧‧‧Glass substrate (transparent substrate)

6‧‧‧Sheet shaped body

6a‧‧ Fresnel lens pattern (optical function pattern)

L1‧‧‧Sunlight incident on optical components

Sunlight collected by L2‧‧‧ optical components

Claims (18)

An optical element comprising: a light-transmitting substrate; and a sheet-shaped molded body made of an organic resin having an optical function pattern on one surface and a light-transmissive substrate on the other surface; wherein the sheet-like molding is performed The body has a tensile modulus of 1500 MPa or less, a linear expansion coefficient of 7.0×10 ⁻⁵ /° C. or less, and an average transmittance of at least 8 % of the visible light wavelength band at a thickness of 400 μm, and a haze value of 1.0% or less; when irradiated with ultraviolet light at an illuminance of 1 kW/m ² for 600 hours using a metal halide lamp, the average light transmittance at a wavelength band of at least 350 nm to 600 nm is less than 2%. . The optical element according to claim 1, wherein the light-transmitting substrate is made of a glass substrate. The optical element according to claim 1 or 2, wherein the sheet-like forming system is formed using a thermoplastic polymer composition containing an acrylic block copolymer (A) and an acrylic resin (B); and the above thermoplastic polymer In the composition, the acrylic block copolymer (A) is an acrylic block copolymer having at least one structure in the molecule: at both ends of the polymer block (a1) mainly composed of an acrylate unit, respectively Bonding a polymer block (a2) mainly composed of a methacrylate unit; and having a weight average molecular weight of 10,000 to 100,000; The acrylic block copolymer (A) contains an acrylic block copolymer (A1) having a polymer block (a2) content of 40% by mass or more and 80% by mass or less; and a polymer block (a2) The acrylic block copolymer (A2) having a content of 10% by mass or more and less than 40% by mass; the acrylic resin (B) is mainly composed of a methacrylate unit; the acrylic block copolymer (A) and an acrylic resin ( The mass ratio of B) [(A)/(B)] is 97/3 to 10/90. The optical element according to claim 1, wherein the sheet-like formed body contains an ultraviolet absorber. The optical element according to claim 1, wherein the light-transmitting substrate contains an ultraviolet absorber. The optical element according to claim 1, wherein an ultraviolet absorbing layer is formed on a surface of the light-transmitting substrate opposite to a surface on which the sheet-shaped formed body is followed. The optical element according to claim 1, wherein the surface of the light-transmitting substrate opposite to the surface of the sheet-shaped formed body is subjected to an antifouling treatment. The optical element according to claim 1, wherein the surface of the light-transmitting substrate opposite to the surface of the sheet-shaped formed body is subjected to an anti-reflection treatment. The optical element according to claim 1, wherein the peeling strength of the sheet-like molded body following the light-transmitting substrate is 25 N/25 mm or more. The optical element according to claim 1, wherein after the sheet-like molded body is subjected to one of plasma treatment, excimer treatment, and corona treatment on the adhesion surface of the light-transmissive substrate, The light-transmitting substrate is followed by the bonding surface. The optical element according to claim 1, wherein the optical function pattern formed on the sheet-like formed body is a Fresnel lens pattern. A concentrating solar power generation device comprising: an optical element for collecting sunlight; and a solar cell element that receives sunlight collected by the optical element and performs photoelectric conversion; wherein the optical component is a patent application scope 11 items of optical components. The optical element according to claim 3, wherein at least one of the sheet-shaped molded body and the light-transmitting substrate contains an ultraviolet absorber. The optical element according to claim 13, wherein the optical function pattern formed on the sheet-like formed body is a Fresnel lens pattern. A concentrating solar power generation device comprising: an optical element for collecting sunlight; and a solar cell element for receiving sunlight collected by the optical element and performing photoelectric conversion; wherein the optical component is the patent application scope 14 The optical component of the item. The optical element according to claim 3, wherein an ultraviolet absorbing layer is formed on a surface of the light-transmitting substrate opposite to a surface on which the sheet-shaped formed body is followed. The optical element according to claim 16, wherein the optical functional pattern formed on the sheet-like formed body is a Fresnel lens pattern. A concentrating solar power generation device comprising: an optical element for collecting sunlight; and a solar cell element for receiving sunlight collected by the optical element and performing photoelectric conversion; wherein the optical component is the patent application scope 17 The optical component of the item.